The present invention relates to an electrically heated floor mat adapted to heat the feet and lower body portions of a person standing on the mat or seated in a chair resting thereon. In the latter case, the mat is normally provided with a heated apron portion extending from one side thereof on which the occupant of the chair usually rests his feet. Planar heating elements, and more particularly heated floor mats, have been proposed. Typically, prior art floor mats are heavy and stiff and therefor awkward to handle. Mats have been proposed which are flexible, but these typically are gouged by chair legs, sharp heels, etc.
The prior art suggests many forms of planar heating elements or floor mats. The following U.S. Pat. Nos. disclose heating units of various types.
2,277,772, 2,299,162 and 2,404,736 to L. Marick, and 3,400,254 to Takemori disclose fabric heating devices which incorporate a heat-generating layer. PA0 2,473,183 to Watson discloses the use of carbon black in combination with a copolymer, such as vinyl chloride and vinyl acetate. PA0 2,540,295, Schreiber discloses a rigid panel heater adapted for use in the wall or ceiling. PA0 2,612,585 discloses the use of rubber or synthetic rubber in a floor mat. PA0 3,344,385, Bartos discloses the use of natural or synthetic rubber containing electrically-conductive particles suspended in a flexible or stretchable carrier. PA0 3,513,297, Jordan discloses heat-radiating rugs or the like containing enclosed filaments of an electrical resistance material. PA0 3,547,725 discloses heat-expandable plastic, such as a polyvinyl chloride-acetate copolymer. PA0 3,553,834, Olstowski et al. discloses a carpet having a conventional backing layer beneath which lies an electrically conductive graphite layer and a second conventional backing layer. PA0 3,657,516, Fujihara discloses a panel type of heater which, though flexible, is not resilient and is not capable of bearing the high loads typically encountered by chair-supporting floor mats. PA0 3,749,886, Michaelsen discloses an electrically heated floor mat having a carbon-loaded sheet. The sheet and its cover may be fabricated of rubber and vulcanized together. PA0 3,790,753, Miller discloses the use of a styrene butadiene rubber in combination with a heating wire network. PA0 3,858,144, Bedard et al. discloses incorporating carbon black in various polymers. PA0 3,859,504 discloses the use of a polyethylene in combination with heating elements. PA0 3,878,362 and 3,900,654, Stinger disclose various chemical compositions for heated structures. PA0 2,458,184, 2,544,547, 2,559,077, 2,782,289, 3,281,579, 3,359,524 and 3,621,192 are also of interest.